PROJECT ABSTRACT For over two decades, blacks and Hispanics have been less likely to receive kidney transplantation than non- Hispanic whites (NHWs), especially from a living donor (LD). Many studies have focused on recipient-related barriers that may contribute to these disparities, but less attention has been paid to how these disparities may arise during recipient and LD evaluation, LD selection, and LD follow-up. For instance, our current system for the evaluation of transplant candidacy recommends referral to transplant centers when the recipient's estimated glomerular filtration rate (eGFR) is < 30mL/min/1.73 m2, and allows for waitlist registration when the eGFR is <20mL/min/1.73 m2. However, kidney disease is known to progress more rapidly among blacks and Hispanics (vs. NHWs), so donors to a black or Hispanic (vs. NHW) recipient may have less time to complete their workup before the need for dialysis arises in the recipient. Black donors have also been noted to have higher risk of developing end-stage renal disease (ESRD) compared to white donors after donation. Heightened awareness of the higher ESRD risk among prior black LDs may predispose to reduced acceptance of even healthy black living donor candidates (the majority of whom donate to black recipients), thereby diminishing the pool of LDs. Finally, lack of consistent medical follow-up of prior LDs may reduce opportunities for early prevention and intervention to reduce risk factors for the development of CKD, especially among black or Hispanic LDs. Sparse data are available regarding whether post-donation health monitoring differs by race/ethnicity, and whether risk factors for chronic kidney disease (CKD) could be more optimally managed to mitigate the higher risk of ESRD among prior black/Hispanic LDs. If outcomes among black or Hispanic donors could be improved, access of black and Hispanic recipients to LDs could also improve. In this proposal, our goal is to examine whether 1) use of a risk-based threshold (vs. an absolute eGFR threshold) to guide when we refer patients for transplant candidacy (and donor) evaluation may improve inequities in the time available for transplant preparation by race/ethnicity (Aim 1); 2) differential acceptance of black or Hispanic (vs. NHW) donor candidates overall, and by provider or transplant center, are occurring despite the availability of objective metrics of donor ESRD risk (Aim 2); 3) post-donation health monitoring and risk factor modification is inadequate among black and Hispanic (vs. NHW) LDs (Aim 3). To accomplish our aims, we will use electronic health record data collected prospectively and retrospectively from transplant centers across the US (Aims 1-2) and prospectively recruit LDs for Aim 3. Data from this proposal will inform the design of multi- level interventions to improve disparities in transplant outcomes, including 1) better acknowledgement of variations in the rate of CKD progression when planning the timing of transplant referral; 2) increased use of objective metrics of ESRD risk during donor evaluation; and 3) enhanced compliance with post-donation health monitoring with the goal of providing early risk factor modification to improve donor outcomes.